I also dont reccomend saying you are going to give a reading and then dont. It is very frusterating to feel as if others are more important than you simply because you were offered something, decided to take it, never got it, and watched as you were skipped over for others. It happens all the time. Try to be considerate and dont offer too much. Dont burn yourself out on it as this may be something you would like to do in the long run.